CDC Issues Expanded Guidance to Protect Workers from Avian Influenza

CDC has updated its guidance for how people working around animals infected with H5N1 can protect themselves from exposure to the virus, which causes avian influenza or bird flu, according to a Nov. 8 report. The updates include adjustments to CDC’s personal protective equipment recommendations to prioritize work tasks and environments in which workers are at higher risk for H5N1 exposure. Higher risk tasks include culling infected poultry, caring for sick cows, or working in a milking parlor. CDC also now recommends offering influenza A(H5) testing and the antiviral medication oseltamivir to asymptomatic workers who report either not wearing PPE or experiencing a PPE failure during a high-risk exposure to H5N1. Oseltamivir may be used to treat people with H5N1 infection, as well as to prevent infection after exposure, which is known as post-exposure prophylaxis. CDC stresses that the risk of H5N1 infection among the general population is low. However, strengthening protections for farm workers is important to reduce the risk of H5N1 transmission from sick animals to workers.

These revisions were prompted by the publication of a study on Nov. 7 in CDC’s Morbidity and Mortality Weekly Report. In this study, CDC worked with state public health departments in Michigan and Colorado to identify dairy workers with evidence of recent H5N1 virus infection. The goals of this study were to measure the prevalence of H5N1 infections, identify risk factors for infection, such as job task and PPE use, and describe illness among people with evidence of infection. According to the MMWR, of the 115 dairy workers who provided blood samples and participated in interviews, eight had antibody levels in their blood serum that indicated recent H5N1 infection. All the workers who had potentially been infected reported that their tasks included milking cows or cleaning the milking parlor. Four workers reported being ill at about the same time cows were ill. In all cases, illness was mild. Three of the eight workers with evidence of infection reported using CDC-recommended eye protection, and none reported using respiratory protection.

A second MMWR, also published on Nov. 7, specifically addressed PPE use by dairy workers in Colorado after H5N1 infection had been detected in cows at their workplaces. Although use of all PPE was low among workers before and after detection of the virus in cattle herds, use of eye protection increased 40 percent among workers who milked cows in the week after detection, the second study found.

Both studies noted the difficulty of encouraging PPE use among dairy workers, who must often work in hot, tight spaces where unrestricted vision is important. Moreover, a majority of the workers who participated in the first study spoke Spanish, including all the workers with evidence of infection. CDC recommends culturally appropriate outreach to dairy workers in their spoken languages about the risk of infection and the need for preventive measures such as PPE.

More information, including links to CDC’s interim guidance for avian influenza, may be found on the agency’s website.